Problems using Collabora with Nextcloud AIO, possibly because of self-signed certificate?

Hey @tobii welcome to the nextcloud community :waving_hand:

nope, neither “collabora” nor “onlyoffice” will work without a valid SSL certificate.

self-signed certificates render your Nextcloud instance virtually unusable, which is why valid SSL certificates are always recommended.

there is absolutely no reason not to make a sharing service like Nextcloud publicly available. Lets Encrypt certificates are quick and easy to manage.